Heretofore, luffing cranes which are used for lifting and shifting loads in substantially horizontal planes have included substantial amounts of rigging, including booms and extensions for booms. It is desirable, when shifting loads, that after the load is raised it can be shifted in a substantially horizontal plane to a remote site. Normally, when the boom of most conventional cranes is raised as the load is being shifted from one site to a remote site, an operator is required to manipulate at least two levers. One lever is used for raising the boom of the crane, while the other lever is used for manipulating the load line so as to maintain the load in a substantially horizontal plane as the boom is raised for shifting the load to a remote site. This requires substantial skill of an operator. If the operator did not manipulate the load line to maintain the load at the same vertical level as the load was being shifted to a remote site, then additional power would be required to raise the boom of the crane. This, in turn, would require the boom and mast of the crane to be more heavily constructed.
A typical example of a luffing crane is disclosed in U.S. Pat. No. 3,685,668 entitled, "Convertible Level Luffing Crane." Another typical example of a luffing crane is disclosed in U.S. Pat. No. 2,401,238 entitled, "Conical Type Level Luffing Device for Derricks and Jib Cranes."